Neuroblastoma is a tumor derived from primitive cells of the sympathetic nervous system. Rapidly growing neuroblastoma cells are exposed to low oxygen levels (hypoxia) as the tumor outstrips its blood supply. Hypoxia has been proposed to contribute to a more aggressive and therapy-resistant phenotype in neuroblastoma. However, the mechanisms responsible for hypoxia-mediated neuroblastoma aggressiveness and the genes involved are largely unknown. Accordingly, the BROAD, LONG-TERM OBJECTIVE of this research project is to use neuroblastoma as a model system to elucidate the molecular mechanisms of how hypoxia is involved in oncogenesis with the aim of identifying novel therapeutic targets. The central hypothesis is that a concerted interplay between hypoxia inducible factors, c-Myc, N-Myc and Notch plays a pivotal role in hypoxia-mediated progression of neuroblastoma. Based on this, THREE SPECIFIC AIMS will be pursued: Specific Aim 1 is to evaluate the effects of hypoxia on neuroblastoma cell lines in vitro;Specific Aim 2 is to investigate the molecular mechanisms responsible for hypoxia induced effects on neuroblastoma cell lines;Specific Aim 3 is to examine hypoxia mediated molecular signatures in xenograft animal models and human patient tumor samples. To achieve these goals, I will combine different methods of biochemistry, cell biology, genetics, immunochemistry, and animal modeling to investigate how hypoxia regulates neuroblastoma behavior using in vitro cell cultures, mice, and primary human patient samples. The RATIONALE of the proposed research is that, once the mechanisms responsible for hypoxia-mediated progression of neuroblastoma are determined, this information can be used for effective prognosis and/or treatment of patients. Meanwhile, it also provides important clues for studying other tumor types as hypoxia is a hallmark of all solid neoplasms. PUBLIC HEALTH RELEVANCE: Neuroblastoma is one of the most frequent childhood cancers and causes 15% of cancer-related death in children. The prevalence is about one case in 7000 live births, and there are about 700 new cases each year in the United States. Despite the array of chemotherapeutic agents presently available, the overall long-term disease free survival rate of neuroblastoma patients remains low. This research aims to identify novel therapeutic targets and is of great significance to public health.